Endocrine Abstracts

In acromegaly, treatment with somatostatin analogs (SSA) normalizes growth hormone (GH) and insulin-like growth factor 1 (IGF1) secretion in about half of the patients. Usually, the disease relapses biochemically within few months after treatment withdrawal.

We present two acromegalic patients, women of 49 and 53 years at diagnosis, respectively, who achieved stable remission of the disease after medical treatment withdrawal. One had a microadenoma, the other a macroadenoma; no visual field defect. Both underwent transsphenoidal surgery as first line treatment, and had hypersecreting remnant tumors, treated with SSA.

In the first case, the first evaluation at 2 months after surgery revealed elevated GH nadir in OGTT (GHn) of 8.3 ng/ml, with IGF1 of 2.66× upper limit of normal (ULN). The pituitary remnant was 9/8/12 mm and remained stable until present. She received medical treatment for 3years, achieving disease control only on Octreotide LAR 30 mg/28 days associated with CAB 2 mg/week (random GH 0.85 ng/ml, normal IGF1). Currently, 6 months and two evaluations after medication withdrawal, she has normal GHn in OGTT (0.5–0.94 ng/ml) and stable IGF1 of 1.2×ULN.

Two months after pituitary surgery, the second patient had a mildly elevated GHn in OGTT (1.2 ng/ml), with IGF1 of 1.36×ULN and a pituitary mass of 11.5/7/13.5 mm. For 3 years, she received Octreotide LAR 20 mg/28 days, during which random GH was 0.28–0.33 ng/ml, with normal IGF1. Now, 1.5 years and three evaluations after SSA withdrawal, she has normal GH nadir in OGTT (0.7–0.3 ng/ml), IGF1 of 1.1×ULN and a stable pituitary nodule (4/6 mm). She received CAB 1 mg/week for 4 months, which did not reduce this IGF1 level.

Conclusion: In a few patients with acromegaly, treatment with somatostatin analogs may induce a prolonged remission of GH hypersecretion that may persist years after treatment discontinuation. Long-term monitoring will decide if this is a real cure of the disease or just a prolonged inhibition of the tumor secretion. Thus, intermitent discontinuation of the long-term SSA treatment seems justified in controlled patients with acromegaly.